Escherichia coli Alpha-Hemolysin HlyA Induces Host Cell Polarity Changes, Epithelial Barrier Dysfunction and Cell Detachment in Human Colon Carcinoma Caco-2 Cell Model via PTEN-Dependent Dysregulation of Cell Junctions

Escherichia coli (E. coli) of the B2 phylotype reside in human and animal intestines. The bacteria possess pathogenicity factors such as α-hemolysin (HlyA) that can induce intestinal epithelial leaks. We addressed the questions which host cell processes were dysregulated by E. coli HlyA that can potentiate intestinal diseases. The colon carcinoma cell line Caco-2 was infected by HlyA+ E. coli. Cell polarity regulation was analyzed by live cell imaging for the phosphatidylinositol-4,5-bisphosphate (PIP2) abundance. In Caco-2 monolayers, transepithelial electrical resistance was measured for characterization of barrier function. Cell proliferation and separation were assessed microscopically. Epithelial regulation and cell signaling were analyzed by RNA-Seq and Ingenuity Pathway Analysis (IPA). Our main findings from E. coli HlyA toxinogenicity in the colon carcinoma cell line are that (i) PIP2 at the membrane decrease, (ii) PTEN (phosphatase and tensin homolog) inhibition leads to cell polarity changes, (iii) epithelial leakiness follows these polarity changes by disruption of cell junctions and (iv) epithelial cell detachment increases. HlyA affected pathways, e.g., the PTEN and metastasis signaling, were identified by RNA-Seq bioinformatics calculations in IPA. In conclusion, HlyA affects cell polarity, thereby inducing epithelial barrier dysfunction due to defective tight junctions and focal leak induction as an exemplary mechanism for leaky gut.

The Inhibition of Proliferation and Invasion of Human Colon Carcinoma Cell Line (Caco-2 cells) by Cell-free Supernatants from Lactobacillus Rhamnosus and Lactobacillus Acidophilus

Background: The epidemiological studies indicated that colorectal cancer is one of the most common types of cancer in the world and is considered a leading cause of cancer-related death. The present study aimed to investigate the inhibitory effect of lactobacillus acidophilus supernatant (LAS) and lactobacillus rhamnosus supernatant (LRS) on the growth and invasiveness of the human colon carcinoma cell line (Caco2) in-vitro. Methods: In this experimental study, the anti-proliferative activity and anti-invasion potential of LAS and LRS were determined by MTT and transwell chambers assays, respectively. The expression of mitochondrial membrane potential-9 (MMP-9) and matrix metalloproteinase-12 (MMP12) genes were analyzed by real-time PCR.Results: The results indicated that supernatants of these two lactobacilli had cytotoxic effects on Caco-2 cells at a concentration of 25% v/v and higher. Thus, the minimum concentrations (25% V/V) of supernatants were chosen for further experiments. LAS and LRS could significantly suppress the invasiveness of Caco-2 cells. Also, the expression of MMP12 was significantly increased in Caco-2 cells when treated with LAS, whereas LRS had no significant effect on the invasive capacity and the gene expression levels of MMP12. The expression of MMP-9 was statistically decreased in Caco2 cells treated with LAS and LRS (P<0.00001).Conclusion: In general, it was shown that LAS and LRS exert anti-cancer activity against the growth, invasion, and metastasis of Caco2 cells in-vitro. It seems that these two bacteria could be used as prophylactic and therapeutic agents for the prevention and treatment of colorectal cancer.

HCMV-Mediated Interference of Bortezomib-Induced Apoptosis in Colon Carcinoma Cell Line Caco-2

Human cytomegalovirus (HCMV) has been implicated in the development of human malignancies, for instance in colon cancer. Proteasome inhibitors were developed for cancer therapy and have also been shown to influence HCMV infection. The aim of this study was to investigate if proteasome inhibitors have therapeutic potential for colon carcinoma and how this is influenced by HCMV infection. We show by immunofluorescence and flow cytometry that the colon carcinoma cell line Caco-2 is susceptible to HCMV infection. Growth curve analysis as well as protein expression kinetics and quantitative genome analysis further confirm these results. HCMV has an anti-apoptotic effect on Caco-2 cells by inhibiting very early events of the apoptosis cascade. Further investigations showed that HCMV stabilizes the membrane potential of the mitochondria, which is typically lost very early during apoptosis. This stabilization is resistant to proteasome inhibitor Bortezomib treatment, allowing HCMV-infected cells to survive apoptotic signals. Our findings indicate a possible role of proteasome inhibitors in colon carcinoma therapy.

Are Compounds Membrane-Associated or Present in the Cytosol? A Study Using Polyphenols in a Colon Carcinoma Cell Line Model

Purpose We investigated the cytosolic and membrane-associated contents of polyphenols after 4 hours of incubation (50 μM of each polyphenol) in the colon carcinoma cell line T84 using a novel, rapid, and convenient method based on permeabilization of the cell membrane using digitonin. The colon carcinoma cell line was used to investigate the intestinal uptake of polyphenols present in apple products. Recent Findings The results showed that hydroxycinnamic acids (caffeic and 5-caffeoylquinic acid) were only detected in the cytosolic fractions. In contrast, 0.3 to 8.2% of the initial concentrations (50 μM) of the flavonoids phloretin, quercetin, phloretin 2′-O-glucoside, and quercetin 3-O-rhamnoside were found in the membrane-associated fractions. In the cytosolic fractions, 0.2–2.9% of these compounds were detected, corresponding to 25 to 40% of the total cell-associated (cytosolic plus membrane-associated fractions) polyphenol content. Summary Our results showed that after uptake, polyphenols were present in the cytosolic fraction of the cells as well as associated with the cell membrane. The presented method provides a useful in vitro tool for determining biologically active compounds in cellular fractions.

Lipidomics reveals insights on the biological effects of copper oxide nanoparticles in a human colon carcinoma cell line

Metabolomics-based approach provides insights to the effects of copper oxide nanomaterials in mammalian cells.